1. Field of the Invention
This invention belongs to the field of agricultural chemistry, and provides a series of new herbicides which are 2-methylamino-4-acyl-4,5-dihydro-1,3,4-thiadiazoles. The compounds are particularly useful for the preemergence control of pigweed (Amaranthas species) and foxtail (Setaria species).
2. State of the Art
The thiadiazol-2-ylureas have been studied as herbicides for some years, especially as herbicides for the total control of vegetation. Patent publications which are typical include South African Pat. No. 69/1559, of Cebalo, and British Pat. Nos. 1,297,147, of Metzger et al., 1,276,925, of Rucker et al., 1,195,672, of Mobil Oil Corp., and 1,266,172, of Air Products and Chemicals Company. Such compounds are fully unsaturated thiadiazoles, and have a urea group with various substitutions at the 2-position of the thiadiazole ring.
Other interesting publications include Yandovskii and Zamorina, Zh. Org. Khim. 12, 457-61 (1976), C.A. 85, 21223 (1976), showing 4-acetyl-5,5-dialkyl-2-(H or methyl)-4,5-dihydro-1,3,4-oxadiazoles, and Yandovskii et al., Zh. Org. Khim. 12, 435-39 (1976), showing related oxadiazolines; and Werber et al., J. Het. Chem. 12, 841-44 (1975), C.A. 84, 74184 (1976), and J. Het. Chem. 12, 581-83 (1975), C.A. 83, 97116 (1975), showing 2-acyl-4-alkyl-5-imino-4,5-dihydro-1,3,4-thiadiazoles.